Chania's nightlife is built around its Venetian harbour, and the setting does most of the work. Stone buildings that have been standing for centuries now house cocktail bars and wine terraces looking out over the water. The pace is unhurried. People linger.
The waterfront promenade is where most visitors start, and for good reason, the outdoor seating, the harbour lights, and the general atmosphere make it one of the more attractive places to spend an evening anywhere in Greece. The eastern section of the harbour tends towards more upscale bars and seafood restaurants. The western side has more casual tavernas and local spots where the clientele is less tourist-heavy.
Move away from the waterfront into the old town's narrow alleys and the character shifts slightly, more intimate, quieter, with wine bars and traditional tavernas tucked into converted Venetian buildings. Cretan music here means the lyra and laouto, not the bouzouki, and venues that feature live traditional music are worth seeking out. Most of Chania's venues are seasonal, operating at full capacity from May through October. Summer evenings, with outdoor terraces open late and the harbour busy but not overwhelming, are when the city is at its best after dark.
Chania suits couples, slower travellers, and anyone who wants their evening to feel like part of the place rather than separate from it. It is not a city for large clubs or late-night dancing. If that is what you are after, Heraklion is the better choice.